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+--- Thread: BiPap causing hi AHI (/Thread-BiPap-causing-hi-AHI)
BiPap causing hi AHI - brianwood619 - 05-07-2015
Ok so I'm almost two weeks into BiPap and I am noticing my AHI has gone from .3 on CPAP to anywhere between 20 and 30 on BiPap. The machine has constantly been pushing 22-24 on pressure each night and I am waking up at least twice to my mask burping from pressure. my son has consistently been at 18-22 on his pressure but his ahi has been less than 1.0 since starting therapy with no complications......any ideas why my ahi has climbed so much
RE: BiPap causing hi AHI - Sleeprider - 05-07-2015
What are all the settings? Min EPAP, Max EPAP, Pressure support, IPAP etc.?
What events make up your AHI now, CA, H or OA?
I suspect your AHI is CA and H, and you are too well ventilated, but please post more information.
RE: BiPap causing hi AHI - brianwood619 - 05-07-2015
Mode: VAuto
Max Ipap: 25.0
Min Epap: 8.0
PS: 9.0
Ti Max: 2.4
Ti Min: 0.3
Trigger: Med
Cycle: Medium
This is what it was set at from the sleep lab prior to going home.
All apneas have been central
RE: BiPap causing hi AHI - justMongo - 05-07-2015
(05-07-2015, 10:55 AM)brianwood619 Wrote: Mode: VAuto
Max Ipap: 25.0
Min Epap: 8.0
PS: 9.0
Ti Max: 2.4
Ti Min: 0.3
Trigger: Med
Cycle: Medium
This is what it was set at from the sleep lab prior to going home.
All apneas have been central
So, IPAP will range from 17 to 25. While the relationship of:
IPAP-EPAP=PS=9 will be held.
So, EPAP will range from 8 to 16.
Keeping in mind that I have no formal medical education, I would guess that with that wide split in PS, you are blowing off too much CO2 resulting in suppression of the central ventilator drive in the brain -- end result, central apneas.
What is the duration of flagged centrals?
RE: BiPap causing hi AHI - brianwood619 - 05-07-2015
So the pressure support could be causing this?
RE: BiPap causing hi AHI - Sleeprider - 05-07-2015
That was my original hunch. I think you should first give your doctor an opportunity to advise on this. Your pressure support is too high and you're being over ventilated. For most people in normal respiration, a PS of 5.0 is plenty to provide respiratory support without over-ventilating. By the time PS equals or exceeds 9.0 the machine breaths for you. If you are not treating chronic central apnea or complex apnea (this is not a ASV), you will over ventilate and experience centrals for the reason explained by justMongo.
And for the record, like JM, this is JMHO not medical advice.
RE: BiPap causing hi AHI - brianwood619 - 05-07-2015
Thanks for the input, I'm a veteran on cpap and a newbie on biPap...lol
RE: BiPap causing hi AHI - vsheline - 05-09-2015
(05-07-2015, 02:37 PM)brianwood619 Wrote: Thanks for the input, I'm a veteran on cpap and a newbie on biPap...lol
Hi Brian,
I suggest lowering PS to 6 and consulting with your doctor.
Unless you have a lung disease/condition, having your Pressure Support at 9 seems very high to me. In addition to causing too many Central Apneas, it might also be raising your SpO2 too high. SpO2 is the percentage of O2 Saturation as measured using a Pulse Oximeter. I think an ideal range to stay in while sleeping would be 94% to 96%, but some think anything above around 90% is usually okay. I think 88% is considered to be too low.
When using Pressure Support higher than around 5, I suggest occasionally wearing a recording Pulse Oximeter. I think Supplier 19 sells them. (A link to the Supplier List is at top of each forum page.) The kind that are worn like a watch with separate finger sensor cup are more comfortable to wear all night and I think provide more consistent measurements.
Here are some articles on the dangers of having too much O2 in our system, which I think can be caused by using too much Pressure Support.
http://www.emsworld.com/article/10915304/the-dangers-of-giving-too-much-oxygen
http://www.ems1.com/columnists/mike-mcevoy/articles/1308955-Can-oxygen-hurt/
Take care,
--- Vaughn
RE: BiPap causing hi AHI - MobileBasset - 05-19-2015
I had horrible sleep with high CA events when my PS was originally set to 6. I reset the PS to 4 and it all cleared up. When it was too high I could feel the pulsing of the pressure changes.